/*
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 *    RemovePercentage.java
 *    Copyright (C) 2002-2012 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.filters.unsupervised.instance;

import java.util.Enumeration;
import java.util.Vector;

import weka.core.Capabilities;
import weka.core.Capabilities.Capability;
import weka.core.Instance;
import weka.core.Instances;
import weka.core.Option;
import weka.core.OptionHandler;
import weka.core.Utils;
import weka.core.WeightedAttributesHandler;
import weka.filters.Filter;
import weka.filters.UnsupervisedFilter;

/**
 * <!-- globalinfo-start --> A filter that removes a given percentage of a
 * dataset.
 * <p/>
 * <!-- globalinfo-end -->
 * 
 * <!-- options-start --> Valid options are:
 * <p/>
 * 
 * <pre>
 * -P &lt;percentage&gt;
 *  Specifies percentage of instances to select. (default 50)
 * </pre>
 * 
 * <pre>
 * -V
 *  Specifies if inverse of selection is to be output.
 * </pre>
 * 
 * <!-- options-end -->
 * 
 * @author Richard Kirkby (eibe@cs.waikato.ac.nz)
 * @author Eibe Frank (eibe@cs.waikato.ac.nz)
 * @version $Revision$
 */
public class RemovePercentage extends Filter implements UnsupervisedFilter, OptionHandler, WeightedAttributesHandler {

    /** for serialization */
    static final long serialVersionUID = 2150341191158533133L;

    /** Percentage of instances to select. */
    private double m_Percentage = 50;

    /** Indicates if inverse of selection is to be output. */
    private boolean m_Inverse = false;

    /**
     * Gets an enumeration describing the available options..
     * 
     * @return an enumeration of all the available options.
     */
    @Override
    public Enumeration<Option> listOptions() {

        Vector<Option> newVector = new Vector<Option>(2);

        newVector.addElement(new Option("\tSpecifies percentage of instances to select. (default 50)\n", "P", 1, "-P <percentage>"));

        newVector.addElement(new Option("\tSpecifies if inverse of selection is to be output.\n", "V", 0, "-V"));

        return newVector.elements();
    }

    /**
     * Parses a given list of options.
     * <p/>
     * 
     * <!-- options-start --> Valid options are:
     * <p/>
     * 
     * <pre>
     * -P &lt;percentage&gt;
     *  Specifies percentage of instances to select. (default 50)
     * </pre>
     * 
     * <pre>
     * -V
     *  Specifies if inverse of selection is to be output.
     * </pre>
     * 
     * <!-- options-end -->
     * 
     * @param options the list of options as an array of strings
     * @throws Exception if an option is not supported
     */
    @Override
    public void setOptions(String[] options) throws Exception {

        String percent = Utils.getOption('P', options);
        if (percent.length() != 0) {
            setPercentage(Double.parseDouble(percent));
        } else {
            setPercentage(50.0);
        }
        setInvertSelection(Utils.getFlag('V', options));

        if (getInputFormat() != null) {
            setInputFormat(getInputFormat());
        }

        Utils.checkForRemainingOptions(options);
    }

    /**
     * Gets the current settings of the filter.
     * 
     * @return an array of strings suitable for passing to setOptions
     */
    @Override
    public String[] getOptions() {

        Vector<String> options = new Vector<String>();

        options.add("-P");
        options.add("" + getPercentage());
        if (getInvertSelection()) {
            options.add("-V");
        }

        return options.toArray(new String[0]);
    }

    /**
     * Returns a string describing this filter
     * 
     * @return a description of the filter suitable for displaying in the
     *         explorer/experimenter gui
     */
    public String globalInfo() {

        return "A filter that removes a given percentage of a dataset.";
    }

    /**
     * Returns the tip text for this property
     * 
     * @return tip text for this property suitable for displaying in the
     *         explorer/experimenter gui
     */
    public String percentageTipText() {

        return "The percentage of the data to select.";
    }

    /**
     * Gets the percentage of instances to select.
     * 
     * @return the percentage.
     */
    public double getPercentage() {

        return m_Percentage;
    }

    /**
     * Sets the percentage of intances to select.
     * 
     * @param percent the percentage
     * @throws IllegalArgumentException if percentage out of range
     */
    public void setPercentage(double percent) {

        if (percent < 0 || percent > 100) {
            throw new IllegalArgumentException("Percentage must be between 0 and 100.");
        }
        m_Percentage = percent;
    }

    /**
     * Returns the tip text for this property
     * 
     * @return tip text for this property suitable for displaying in the
     *         explorer/experimenter gui
     */
    public String invertSelectionTipText() {

        return "Whether to invert the selection.";
    }

    /**
     * Gets if selection is to be inverted.
     * 
     * @return true if the selection is to be inverted
     */
    public boolean getInvertSelection() {

        return m_Inverse;
    }

    /**
     * Sets if selection is to be inverted.
     * 
     * @param inverse true if inversion is to be performed
     */
    public void setInvertSelection(boolean inverse) {

        m_Inverse = inverse;
    }

    /**
     * Returns the Capabilities of this filter.
     * 
     * @return the capabilities of this object
     * @see Capabilities
     */
    @Override
    public Capabilities getCapabilities() {
        Capabilities result = super.getCapabilities();
        result.disableAll();

        // attributes
        result.enableAllAttributes();
        result.enable(Capability.MISSING_VALUES);

        // class
        result.enableAllClasses();
        result.enable(Capability.MISSING_CLASS_VALUES);
        result.enable(Capability.NO_CLASS);

        return result;
    }

    /**
     * Sets the format of the input instances.
     * 
     * @param instanceInfo an Instances object containing the input instance
     *                     structure (any instances contained in the object are
     *                     ignored - only the structure is required).
     * @return true because outputFormat can be collected immediately
     * @throws Exception if the input format can't be set successfully
     */
    @Override
    public boolean setInputFormat(Instances instanceInfo) throws Exception {

        super.setInputFormat(instanceInfo);
        setOutputFormat(instanceInfo);
        return true;
    }

    /**
     * Input an instance for filtering. Ordinarily the instance is processed and
     * made available for output immediately. Some filters require all instances be
     * read before producing output.
     * 
     * @param instance the input instance
     * @return true if the filtered instance may now be collected with output().
     * @throws IllegalStateException if no input format has been set.
     */
    @Override
    public boolean input(Instance instance) {
        if (getInputFormat() == null) {
            throw new IllegalStateException("No input instance format defined");
        }

        if (m_NewBatch) {
            resetQueue();
            m_NewBatch = false;
        }

        if (isFirstBatchDone()) {
            push(instance);
            return true;
        } else {
            bufferInput(instance);
            return false;
        }
    }

    /**
     * Signify that this batch of input to the filter is finished. Output() may now
     * be called to retrieve the filtered instances.
     * 
     * @return true if there are instances pending output
     * @throws IllegalStateException if no input structure has been defined
     */
    @Override
    public boolean batchFinished() {

        if (getInputFormat() == null) {
            throw new IllegalStateException("No input instance format defined");
        }

        // Push instances for output into output queue
        Instances toFilter = getInputFormat();
        int cutOff = (int) Math.round(toFilter.numInstances() * m_Percentage / 100);

        if (m_Inverse) {
            for (int i = 0; i < cutOff; i++) {
                push(toFilter.instance(i), false); // No need to copy
            }
        } else {
            for (int i = cutOff; i < toFilter.numInstances(); i++) {
                push(toFilter.instance(i), false); // No need to copy
            }
        }
        flushInput();

        m_NewBatch = true;
        m_FirstBatchDone = true;

        return (numPendingOutput() != 0);
    }

    /**
     * Main method for testing this class.
     * 
     * @param argv should contain arguments to the filter: use -h for help
     */
    public static void main(String[] argv) {
        runFilter(new RemovePercentage(), argv);
    }
}
